U.S. patent application number 13/777942 was filed with the patent office on 2014-08-28 for apparatus, systems and methods for detecting insertion or removal of an audio accessory from an electronic device.
This patent application is currently assigned to Research in Motion Limited. The applicant listed for this patent is Per Magnus Fredrik Hansson, Jens Kristian Poulsen, Yong Zhang. Invention is credited to Per Magnus Fredrik Hansson, Jens Kristian Poulsen, Yong Zhang.
Application Number | 20140241535 13/777942 |
Document ID | / |
Family ID | 51388182 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140241535 |
Kind Code |
A1 |
Poulsen; Jens Kristian ; et
al. |
August 28, 2014 |
APPARATUS, SYSTEMS AND METHODS FOR DETECTING INSERTION OR REMOVAL
OF AN AUDIO ACCESSORY FROM AN ELECTRONIC DEVICE
Abstract
According to one aspect, an electronic device for detecting an
audio accessory. The electronic device includes an audio jack
having at least two detection terminals. The detection terminals
are spaced apart and positioned within a socket of the audio jack
so when an audio plug of the accessory is inserted into the socket
of the audio jack, the detection terminals will be shorted. The
presence of a short between the detection terminals is indicative
that the audio accessory is present.
Inventors: |
Poulsen; Jens Kristian;
(Kitchener, CA) ; Zhang; Yong; (Waterloo, CA)
; Hansson; Per Magnus Fredrik; (Waterloo, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Poulsen; Jens Kristian
Zhang; Yong
Hansson; Per Magnus Fredrik |
Kitchener
Waterloo
Waterloo |
|
CA
CA
CA |
|
|
Assignee: |
Research in Motion Limited
Waterloo
CA
|
Family ID: |
51388182 |
Appl. No.: |
13/777942 |
Filed: |
February 26, 2013 |
Current U.S.
Class: |
381/58 |
Current CPC
Class: |
H04R 29/001 20130101;
G01R 31/50 20200101; H04R 5/04 20130101; H04R 2420/05 20130101 |
Class at
Publication: |
381/58 |
International
Class: |
H04R 29/00 20060101
H04R029/00 |
Claims
1. An electronic device for detecting an audio accessory,
comprising: an audio jack having at least two detection terminals,
the detection terminals including an end terminal adapted to send
audio information to a tip connector of the audio plug and another
detection terminal spaced apart from the end terminal and
positioned within the audio jack so when an audio plug of the
accessory is inserted into the audio jack, the end terminal and
other detection terminal will be shorted; and a detection circuit
adapted to monitor the detection terminals, and when the detection
circuit detects a short therebetween, indicate that the audio
accessory is present.
2. The electronic device of claim 1, wherein the detection circuit
is adapted to apply a bias voltage to one of the detection
terminals.
3. The electronic device of claim 2, wherein the bias voltage is
applied to the end terminal and is outside of an output voltage
range of an audio amplifier.
4. The electronic device of claim 1, wherein the detection circuit
comprises a current source adapted to send a current when the
detection terminals are shorted.
5. The electronic device of claim 1, wherein the detection circuit
comprises tone generator coupled to one of the detection terminals
and a tone detector coupled to the other of the detection
terminals, the tone generator adapted to generate a tone, and
wherein the tone detector detecting the tone is indicative of the
presence of the accessory.
6. The electronic device of claim 5, wherein the tone is inaudible
to a human.
7. An electronic device for detecting an audio accessory,
comprising: an audio jack having at least two detection terminals,
the detection terminals being spaced apart and positioned within a
socket of the audio jack so when an audio plug of the accessory is
inserted into the socket of the audio jack, the detection terminals
will be shorted; wherein the presence of a short between the
detection terminals indicates that the audio accessory is
present.
8. The electronic device of claim 7, wherein the detection
terminals are positioned within the socket so as to be shorted by
the same connector of the audio plug.
9. The electronic device of claim 7, wherein the at least two
detection terminals include an end terminal adapted to send audio
information to a tip connector of the audio plug and another
detection terminal spaced apart from the end terminal.
10. The electronic device of claim 7, wherein a change in state of
the short of the detection terminals is indicative of an insertion
of the accessory or a removal of the accessory.
11. The electronic device of claim 7, wherein the terminals are on
opposite sides of a socket of the audio jack.
12. The electronic device of claim 7, wherein the detection
terminals are at or near a tip-end of the socket and are adapted to
be shorted by a tip connector of the audio plug.
13. The electronic device of claim 7, further comprising a
detection circuit adapted to cooperate with the detection terminals
to detect the accessory.
14. The electronic device of claim 13, wherein the detection
circuit is adapted to apply a bias voltage to one of the detection
terminals.
15. The electronic device of claim 14, wherein the bias voltage is
outside of an output voltage range of an audio amplifier coupled to
another of the detection terminals.
16. The electronic device of claim 13, wherein the detection
circuit comprises a current source adapted to send a current when
the detection terminals are shorted.
17. The electronic device of claim 13, wherein the detection
circuit comprises tone generator coupled to one of the detection
terminals and a tone detector coupled to another of the detection
terminals, the tone generator adapted to generate a tone, and
wherein whether the tone detector detects the tone is indicative of
the presence of the accessory.
18. The electronic device of claim 17, wherein the tone is
inaudible to a human.
19. The electronic device of claim 18, wherein the tone is an
ultrasonic tone.
20. The electronic device of claim 13, wherein the detection
circuit comprises a zero-crossing detector coupled to a detection
terminal opposite an audio amplifier, and wherein the zero-crossing
detector is adapted to indicate that no accessory is present if no
zero-crossing is detected within a particular time.
Description
FIELD
[0001] Embodiments herein relate to electronic devices and in
particular to apparatus, systems and methods for detecting the
insertion or removal (or both) of an audio accessory, such as a
headset, from an electronic device.
Introduction
[0002] Electronic devices, including portable electronic devices
like smart phones and tablets, have gained widespread use and may
provide a variety of functions including telephonic services, text
messaging, playing media such as music and movies, and so on.
[0003] Electronic devices are often used with audio accessories
such as microphones, standalone speakers, headsets or headphones
(for purposes of illustration and explanation, audio accessories
may be illustrated herein as headsets or headphones). Audio
accessories may receive from the electronic device, or transmit to
the electronic device (or both) audio information, which may
include any signals related to audio, such as voice or music or
other sounds, and any instructions or messages or control codes or
other data related to the audio. For example, some electronic
devices have audio jacks that are sized and shaped to receive a
mating audio plug from a headset audio accessory. A user connects
the headset audio accessory to the electronic device by inserting
the audio plug on the headset into the audio jack on the electronic
device. Once connected, audio can be output to the user by the
audio accessory (e.g., via speakers on the audio accessory).
[0004] In some cases, audio accessories may incorporate a
microphone to allow audio signals (e.g., speech) to be sent from
the audio accessory to the electronic device. This may allow the
user to make phone calls using the audio accessory, record voice
memos, control the electronic device using voice commands, and so
on.
[0005] In some cases, an audio accessory may include one or more
buttons or other input devices to control the electronic
device.
DRAWINGS
[0006] For a better understanding of the embodiments described
herein, and to show how they may be carried into effect, reference
will now be made, by way of example, to the accompanying
drawings.
[0007] FIG. 1 is a schematic representation of an audio accessory
coupled to an electronic device according to one embodiment;
[0008] FIG. 2 is a schematic diagram of an audio jack with a
movable element adapted to detect an audio accessory;
[0009] FIG. 3 is a schematic diagram of an audio plug received in
the audio jack of FIG. 2;
[0010] FIG. 4 is a schematic diagram of an audio jack according to
one embodiment;
[0011] FIG. 5 is a schematic diagram of an audio plug received in
the audio jack of FIG. 4;
[0012] FIG. 6 is a schematic diagram of an audio jack according to
another embodiment;
[0013] FIG. 7 is a schematic diagram of an audio jack according to
another embodiment;
[0014] FIG. 8 is a schematic diagram of the accessory of FIG.
1;
[0015] FIG. 9 is a schematic diagram of a detection circuit adapted
to apply a bias voltage across the detection terminals;
[0016] FIG. 10 is a schematic diagram of a detection circuit
adapted to send a current across the detection terminals;
[0017] FIG. 11 is a schematic diagram of a detection circuit
adapted to send an inaudible tone across the detection terminals;
and
[0018] FIG. 12 is a schematic diagram of a detection circuit having
a zero-crossing detector.
DESCRIPTION OF VARIOUS EMBODIMENTS
[0019] Generally, some embodiments as described herein may be
implemented on electronic devices, which may include a wide range
of portable electronic devices that can be worn or carried by a
human user, such as mobile phones, smart phones, personal digital
assistants (PDAs), notebooks, laptops, digital audio/video players,
digital audio/video recorders, tablet computers, and so on. The
devices may be handheld, that is, sized and shaped to be held and
carried in a human hand (although some handheld devices may be
attached to clothing or otherwise worn during normal use). In some
appropriate cases, however, the electronic devices may also include
devices that are normally not worn or carried by a human user, for
example a desktop computer, a stereo system, a vehicle audio
system, and so on.
[0020] One aspect as described herein is directed to An electronic
device for detecting an audio accessory, comprising an audio jack
having at least two detection terminals, the detection terminals
including an end terminal adapted to send audio information to a
tip connector of the audio plug and another detection terminal
spaced apart from the end terminal and positioned within the audio
jack so when an audio plug of the accessory is inserted into the
audio jack, the end terminal and other detection terminal will be
shorted, and a detection circuit adapted to monitor the detection
terminals, and when the detection circuit detects a short
therebetween, indicate that the audio accessory is present.
[0021] The detection circuit may be adapted to apply a bias voltage
to one of the detection terminals. The bias voltage may be applied
to the end terminal and is outside of an output voltage range of an
audio amplifier.
[0022] The detection circuit may include a current source adapted
to send a current when the detection terminals are shorted. The
detection circuit may include a tone generator coupled to one of
the detection terminals and a tone detector coupled to the other of
the detection terminals, the tone generator adapted to generate a
tone, and wherein the tone detector detecting the tone is
indicative of the presence of the accessory. The tone may be
inaudible to a human.
[0023] According to another aspect an electronic device for
detecting an audio accessory, comprising an audio jack having at
least two detection terminals, the detection terminals being spaced
apart and positioned within a socket of the audio jack so when an
audio plug of the accessory is inserted into the socket of the
audio jack, the detection terminals will be shorted, wherein the
presence of a short between the detection terminals indicates that
the audio accessory is present.
[0024] The detection terminals may be positioned within the socket
so as to be shorted by the same connector of the audio plug. The
detection terminals may include an end terminal adapted to send
audio information to a tip connector of the audio plug and another
detection terminal spaced apart from the end terminal.
[0025] A change in state of the short of the detection terminals is
generally indicative of an insertion of the accessory or a removal
of the accessory.
[0026] The terminals may be on opposite sides of a socket of the
audio jack. The detection terminals may be at or near a tip-end of
the socket and are adapted to be shorted by a tip connector of the
audio plug.
[0027] In some embodiments, the electronic device includes a
detection circuit adapted to cooperate with the detection terminals
to detect the accessory. The detection circuit may be adapted to
apply a bias voltage to one of the detection terminals. The bias
voltage may be outside of an output voltage range of an audio
amplifier coupled to another of the detection terminals. The
detection circuit may include a current source adapted to send a
current when the detection terminals are shorted.
[0028] The detection circuit may include a tone generator coupled
to one of the detection terminals and a tone detector coupled to
another of the detection terminals, the tone generator adapted to
generate a tone, and wherein whether the tone detector detects the
tone is indicative of the presence of the accessory. The tone may
be inaudible to a human. In some embodiments, the tone is an
ultrasonic tone.
[0029] In some embodiments, the detection circuit includes a
zero-crossing detector coupled to a detection terminal opposite an
audio amplifier, and wherein the zero-crossing detector is adapted
to indicate that no accessory is present if no zero-crossing is
detected within a particular time.
[0030] On some of electronic devices, especially portable
electronic devices, computer resources (e.g., memory capacity,
processing power and screen space) may be more limited than on
other devices. A portable smart phone, for example, may generally
have a smaller display and less memory capacity than a desktop
computer, which may have a larger display and more memory.
[0031] The concepts as described herein are not necessarily limited
to any particular kind of electronic device, but may be generally
suitable for use on various electronic devices with various
computer resources.
[0032] In some embodiments, the electronic device may be a portable
electronic device, such as a smart phone with communications
capabilities (e.g., voice, data, or both), over a data connection
(e.g., a cellular network), and which is adapted to cooperate with
an audio accessory (e.g., headphones). In this disclosure, elements
may be described as "adapted to" perform or "adapted for"
performing one or more functions. In general, an element that is
adapted to perform a function is suitable for performing the
function, or is configured to perform the function, or is operable
to perform the function, or is otherwise capable of performing the
function.
[0033] In general, it may be desirable to detect when an audio
accessory is coupled to the electronic device. Specifically, it may
be useful to know when an audio accessory is inserted into the
electronic device, or removed from the electronic device (or both),
as this knowledge can be used to selective trigger one or more
actions, such as changing an operational state of the electronic
device.
[0034] For instance, when an audio accessory is removed from the
electronic device it may be desirable to terminate audio output
through the audio jack, activate a speaker on the electronic device
(e.g., for receiver or speakerphone mode), or take some other
action. Alternatively, when an audio accessory is inserted into the
electronic device, it may be desirable to switch to an "accessory"
or "headphone" mode, initiate audio playback via the audio jack,
deactivate a speaker on the electronic device, and so on.
[0035] In order to detect the insertion or removal (or both) of
audio accessories from the audio jack, various approaches may be
used.
[0036] One approach uses a detection pin positioned within the
audio jack on the electronic device. The detection pin senses the
insertion or removal of an audio accessory via a moveable switch.
In particular, the detection pin has at least one movable element,
and the insertion or removal of the audio plug causes that element
to move to either open or close an electrical circuit (depending on
the particular configuration). This opening and closing is
interpreted (e.g., by a processor on the electronic device) as
either an insertion event or a removal event depending on the
particular configuration.
[0037] For example, in a "normally open" configuration, the movable
element is normally not in electrical contact with another terminal
and the electrical circuit is open. However, when the audio
accessory is inserted into the electronic device, the movable
element will move into electrical contact with another terminal,
closing the electrical circuit. This will be registered by the
electronic device as an insertion event. Similarly, when the audio
accessory is removed, the electrical connection between the
terminals will be broken, registering the removal event.
[0038] Alternatively, in a "normally closed" configuration, a first
and second terminal may be in electrical contact until the audio
accessory is inserted into the audio jack. The action of inserting
the audio accessory will break this electrical contact, opening the
circuit, which will be registered as an insertion event. Similarly,
when the audio accessory is removed, the terminals will return to
being in electrical contact, closing the circuit and registering a
removal event.
[0039] Unfortunately, using such a movable element within an audio
jack may be problematic. In particular, lint, dust, sand or various
other types of particles or contaminants can enter the audio jack
and can become lodged between the terminals of the detection pin,
or otherwise interfere with the movement of the movable element,
which can result in detection failures. This failure mode can be
quite common, and up to 2% or more of electronic devices may
experience this condition. When such a failure happens, it may no
longer be possible to properly detect the insertion or removal of
an accessory by use of information from the detection terminal,
which can negatively impact the performance of the electronic
device.
[0040] Accordingly, at least some embodiments herein are directed
at improved techniques for detecting whether an audio accessory is
coupled to an electronic device, particularly for detecting the
insertion or removal (or both) of an audio accessory.
[0041] In one aspect, an audio jack is configured with at least two
detection terminals, which may be located at or near the tip-end of
the socket of the audio jack. The detection terminals are spaced
apart, and in some embodiments may be on opposite sides of the
socket.
[0042] The detection terminals are positioned so when an audio
accessory is coupled to the electronic device, the audio plug of
the accessory will be in electrical contact with both terminals.
More particularly, the same electrical contact on the audio plug
(e.g., namely either the tip, ring or sleeve) will be in electrical
contact with both terminals. That electrical contact thus provides
a short circuit between the detection terminals. As used herein, a
shorting refers to the creation or presence of a short circuit.
Generally speaking, shorting refers to two nodes being electrically
connected such that their voltages are substantially equal to one
another.
[0043] Shorting includes not only strict shorting, in which the two
nodes are electrically connected by being brought in directly in
electrical and physical contact with one another, but also
substantial shorting, in which one or more intermediate elements
(typically having negligible impedance) bridges the two nodes.
[0044] The detection terminals can be monitored, and when a short
circuit (or simply a short) between the detection terminals exists,
the short can be detected (in some cases using one or more
detection circuits as described below). Detection of a short, or
lack of detection of a short, can be used to determine whether an
audio accessory has been inserted or removed.
[0045] More generally, the presence of a short between the
detection terminals suggests that an audio accessory is present,
while the absence of a short suggests that no audio accessory is
present. A change in state (e.g., from detecting a short to not
detecting a short, and vice versa) can be used as an indicator of a
particular removal or insertion event.
[0046] In some embodiments, the detection terminals are provided at
or near the tip end of the socket. In such cases, the tip contact
of the audio plug will short the detection terminals. Positioning
the detection terminals in this location can be beneficial as a
short will generally only occur between the detection terminals
when the audio plug is fully inserted within the audio jack. In
contrast, although it is possible for the detection terminals to be
positioned elsewhere within the socket (e.g., to be shorted by the
sleeve of a TRS jack), this configuration can lead to false reads
that may occur if either the tip contact or ring contact
temporarily shorts the detection terminals as the audio plug is
inserted.
[0047] Since the detection terminals are spaced apart within the
socket (in some cases on opposite sides of the socket), it is less
likely that particles (e.g., lint or dirt) will become stuck in
between the terminals in a manner that interferes with the
detection of the audio accessory. Generally speaking, the detection
terminals are spaced apart in that there is a gap between them such
that they are not in physical contact with one another, although
the distance of the gap is not necessarily the same in all
implementations.
[0048] In some embodiments, a detection circuit cooperates with the
detection terminals to detect the insertion or removal of an audio
accessory (e.g., by monitoring the detection terminals and
detecting the short).
[0049] In particular, in some cases, the end terminal in an audio
jack (which is designed to make electrical contact with the tip
contact of the audio plug to send audio signals to the accessory)
may be used as one of the detection terminals. In other cases, the
detection terminals may be separate from the end terminal (although
the detection terminals and end terminal may all be in contact with
the tip contact at the same time).
[0050] Since the end terminal is normally used to carry left
channel audio information to an audio accessory, the end terminal
normally does not have a fixed voltage. As such, the end terminal
will often carry an audio signal with a voltage that can interfere
with the detection of the accessory via the detection terminals.
Thus, without a suitably configured detection circuit, false
insertion or removal events (or both) might be registered
(depending on the audio signal being sent through to the tip
connector of the audio plug).
[0051] One such detection circuit may bias the detection terminals
using a voltage source with high output impedance and with an
output voltage (higher or lower) that is outside of the normal
output voltage range of the audio amplifier that drives the left
channel. Accordingly, an observed detection voltage can be checked
using a voltage comparator. When a detection voltage is observed
that is higher or lower than any output normally possible from the
audio amplifier, a fairly reliable prediction can be made about the
status of the audio accessory, despite large voltage variations
that might be present in the audio output signal on the left
channel.
[0052] In some embodiments, a controlled current source may be
coupled to the output on the left channel. When the detection
terminals are connected, a well-defined current will run into the
audio amplifier. However, when the detection terminals are
disconnected (e.g., the accessory is unplugged) this current source
will be unable to send out this current, and the output will
immediately swing to the voltage rails. This swing can be detected
by direct observation or from a control voltage of the current
source.
[0053] In another embodiment, it may be possible to use inaudible
tones (e.g., ultrasonic tones) to detect the presence or absence of
the accessory. More particularly, an ultrasonic tone (e.g., a
32.768 kHz tone) may be generated and applied to one of the
detection terminals, while the other detection terminal is
monitored. If the ultrasonic tone is detected at the second
terminal, this indicates that the two terminals have been shorted
and an audio accessory has been inserted. In some embodiments the
high frequency tone may be output directly through the audio
amplifier.
[0054] In some embodiments, it may also possible to exploit the
fact that most audio amplifiers are AC-coupled at the input, and
therefore will have a low output voltage (or zero-crossing) within
a finite amount of time T. Thus, the presence of a zero-crossing
can be monitored at the detection terminal opposite the audio
amplifier; if no zero-crossing is observed within a particular
amount of time (e.g., within 100 milliseconds), this indicates that
the detection terminals are not shorted and no audio accessory is
inserted.
[0055] In some embodiments, zero-crossings could be detected using
a slow threshold detector with a time constant slower than the
input filter and with a detection threshold close to either the
higher or lowest supply voltage of the audio amplifier. In this
case, a high output impedance voltage source may be coupled to one
of the detection terminals.
[0056] In some embodiments, one or more special pulsing methods may
be to detect the presence of multiple different audio plug
configurations (e.g., TRS, TRRS, etc.). For example, inaudible
waveforms may be used during detection to avoid unpleasant
artifacts. This can be generated using pulses with an energy
content lower than the human threshold, or with a frequency that is
outside of the human hearing range (which is normally between
approximately 20 Hz to 20,000 Hz). These pulses may be shaped in
such a way that during the transition of turning on and off these
pulses no audible artifacts occur. This may be done, for example,
by slowly turning on and off the excitation of these waveforms to
ensure that any energy content within the human hearing frequency
range is sufficiently low so as to be generally inaudible.
[0057] During detection, it may be necessary to disconnect any
loads from the detection terminals during a detection sequence. In
some cases this may be done using a switch or by making the
resistance value of the external load sufficiently large such that
it will not be detected as a valid load at the insertion detection
terminal when nothing is connected.
[0058] Reference is now made to FIG. 1, which is a schematic
diagram illustrating an electronic device 12 and an audio accessory
14 coupled thereto via an audio jack 11.
[0059] The electronic device 12 may include any suitable electronic
device, such as a portable smart phone having a display 13, and
which may include a memory, a processor, a communications system
for communicating over a wireless network (e.g., a cellular
network, a Wi-Fi network, etc.) and other functional components as
will be generally understood.
[0060] In some embodiments, the electronic device 12 may have a
physical keyboard 15 (as shown). In some embodiments, the
electronic device 12 may include a touchscreen device, optionally
with or without a physical keyboard 15.
[0061] In this embodiment the audio accessory 14 is a stereo
headphone having two speakers (e.g., a right speaker 16 and a left
speaker 18), although in other embodiments a different number of
speakers could be present. The speakers 16, 18 of the audio
accessory 14 are generally operable to output audio content, such
as music, speech, and so on.
[0062] In this embodiment, the audio accessory 14 also includes a
user control interface 20 for controlling aspects of the electronic
device 12 (e.g., audio volume, changing music tracks, etc.),
although in other embodiments no control interface 20 may be
present.
[0063] In some embodiments, the audio accessory 14 may be a headset
that includes a microphone 30 for receiving audio signals (e.g., a
user's voice) and for sending those audio signals to the electronic
device 12. As shown, in some embodiments the microphone 30 may be
provided with the user control interface 20. Alternatively, the
microphone 30 may be provided at another location on the audio
accessory 14.
[0064] As shown in FIG. 8, in some embodiments the control
interface 20 may include a switch 22 that is adapted to short the
microphone 30 to send control signals to the electronic device 12.
In other embodiments, the control interface 20 may have various
other control schemes.
[0065] In some embodiments, the audio accessory 14 is connected to
the electronic device 12 using an audio plug 50 on the audio
accessory 14 that mates with a corresponding audio jack 11 on the
electronic device 12. In some embodiments, the plug 50 and jack 11
can be of the tip-ring-sleeve (TRS) variety, or a
tip-ring1-ring2-sleeve (TRRS) variety, or other various types. For
example, some audio connectors are in the form of 3.5 mm (1/8'')
miniature plugs and jacks, or other sizes such as 2.5 mm connectors
and 1/4'' connectors. In headsets and other accessories, these
audio connectors are generally used to carry audio signals and
other information between the speakers 16, 18, the microphone 30
and the electronic device 12.
[0066] As discussed above, it may be beneficial to detect when the
audio accessory 14 is inserted into, or removed from, the
electronic device 12 (or both). In particular, the presence or
absence of the audio accessory 14 may be used to trigger the change
of an operational state of the electronic device 12 (e.g.,
switching to speakerphone mode, pausing or resuming audio playback
via the audio jack 11, and so on).
[0067] Accordingly, turning now to FIGS. 2 and 3, illustrated
therein is an audio jack 40 adapted for detecting the insertion or
removal of an audio accessory using a movable element. As shown,
the audio jack includes a socket 35 that can generally be defined
as having a tip-end 35a and an open end 35b. The socket 35 is
adapted to receive an audio plug 50 via the open end 35b, and when
fully inserted the tip contact 52 of the audio plug 50 will
generally be at or near the tip-end 35a of the socket 35.
[0068] The audio jack 40 includes a plurality of operational
terminals adapted to make electrical contact with the audio plug 50
of the audio accessory. In particular, the audio jack 40 includes
an end terminal 41 adapted to make electrical contact with the tip
contact 52 of the audio plug 50, a ring1 terminal 42 adapted to
make electrical contact with the ring1 contact 54, a ring2 terminal
43 adapted to make electrical contact with the ring2 contact 56,
and a sleeve terminal 44 adapted to make electrical contact with
the sleeve contact 58. More particularly, each terminal 41, 42, 43
and 44 has an end portion 41a, 42a, 43a, and 44a, respectively,
adapted to be in physical contact with the contacts 52, 54, 56 and
58 when the audio plug 50 is received within the socket 35 (as
shown in FIG. 3).
[0069] As shown, the audio jack 40 also includes a detection pin
45, which in this embodiment is a "normally closed" detection pin.
In particular, as shown in FIG. 2, without the audio plug 50 a
contact terminal 45a of the detection pin 45 is in electrical
contact with the end terminal 41. Accordingly, an electrical
circuit between the detection pin 45 and the end terminal 41 is
closed.
[0070] However, in this embodiment the end terminal 41 is a movable
element. When the audio plug 50 is inserted into the socket 35, the
tip contact 52 of the audio plug pushes the end terminal 41 and
breaking the electrical contact between the end terminal 41 and the
detection pin 45.
[0071] This change in state can be used to indicate that the audio
accessory has been inserted into the electronic device. However (as
discussed above) lint, dust or other particles can enter the audio
jack 40, and may become stuck between the detection pin 45 and the
end terminal 41, thus inhibiting the formation of an electrical
circuit. Alternatively, such particles can interfere with the
movement of the end terminal 41. Both of these issues can result in
detection failures in which the insertion or removal of an audio
accessory may not be properly recognized.
[0072] Turning now to FIGS. 4 and 5, illustrated therein is an
audio jack 60 according to one embodiment. The audio jack 60
includes a plurality of operational terminals adapted to make
electrical contact with the audio plug 50. In particular, the audio
jack 60 includes an end terminal 61 with a portion 61a adapted to
make electrical contact with the tip contact 52, a ring1 terminal
62 with a portion 62a adapted to make electrical contact with the
ring1 contact 54, a ring2 terminal 63 with a portion 63a adapted to
make electrical contact with the ring2 contact 56, and a sleeve
terminal 64 with a portion 64a adapted to make electrical contact
with the sleeve contact 58.
[0073] In this embodiment, the end terminal 61 serves as a first
detection terminal, and the audio jack 60 also includes a second
detection terminal 65, having a portion 65a adapted to also make
contact with the tip contact 52 of the audio plug 50. The end
portions 61a and 65a of the detection terminals 61, 65 are spaced
apart by a gap distance D. In general, the gap distance D may be
selected to inhibit dust, lint, or other particles from becoming
lodged therebetween. Typical gap distances may be on the order of a
few millimeters, but there is no specific minimum or maximum
distance. In some embodiments, the end portions 61a and 65a of the
detection terminals 61, 65 are on opposing sides of the socket 35
(as suggested by the figures; the detection terminals 61, 65 may
be, but need not be, diametrically opposed) so as to increase the
distance therebetween.
[0074] As shown in FIG. 5, when the audio plug 50 is received in
the audio jack 60, the tip contact 52 is in electrical contact with
both detection terminals 61, 65. Thus, a short is created between
the detection terminals 61, 65, and which is indicative of the
presence of the audio plug 50.
[0075] In this embodiment, the detection terminals 61, 65 are
provided at or near the tip-end 35a of the socket 35. Accordingly,
the detection terminals 61, 65 will generally only indicate the
presence of an audio plug 50 when the audio plug 50 is fully
received within the audio jack 60.
[0076] In other embodiments, the detection terminals may be
provided at other locations within the socket 35, although this may
increase the chance of misreads. For instance, the ring2 terminal
63 could be used as a first detection terminal with a second
detection terminal positioned opposite thereto within the socket
35.
[0077] Turning now to FIG. 6, illustrated therein is a schematic
diagram of an audio jack 70 according to another embodiment.
[0078] The audio jack 70 is generally similar to audio jack 60 and
includes a plurality of operational terminals adapted to make
electrical contact with the audio plug 50. In particular, the audio
jack 70 includes an end terminal 71, a ring1 terminal 72, a ring2
terminal 73, and a sleeve terminal 74. In this embodiment, the end
terminal 71 serves as a first detection terminal, and a second
detection terminal 75 is provided in a spaced apart relationship
thereto.
[0079] In this embodiment, however, the operational terminals are
positioned with a different pattern. In particular, the end
terminal 71 and ring2 terminal 73 are provided on a first side of
the socket 35, while the detection terminal 75, ring1 terminal 72
and sleeve terminal 74 are provided on the opposite side. In
general, terminals 71, 72, 73, 74 and 75 can be placed on the same
side of a connector, or some of the terminals 71, 72, 73, 74 and 75
may be placed on the opposite side, or different embodiments some
of the terminals 71, 72, 73, 74 and 75 may be placed below or above
(or both) the terminals placed on the side of the socket.
[0080] Turning now to FIG. 7, illustrated therein is another audio
jack 80. The audio jack 80 is generally similar to audio jack 60
and includes an end terminal 81, a ring1 terminal 82, a ring2
terminal 83, and a sleeve terminal 84. In this embodiment, the end
terminal 81 serves as a first detection terminal, and a second
detection terminal 85 is provided in a spaced apart relationship
thereto.
[0081] In this embodiment, the end terminal 81, ring1 terminal 82
and sleeve 84 are provided on a first side of the socket 35, while
the detection terminal 85 and ring2 terminal 73 are provided on the
opposite side. There may be benefits with respect to this
embodiment in that the physical size of the connector may be
reduced by placing the terminals on either side of the socket,
thereby making one or more of the physical dimensions of width,
height, or length smaller. Furthermore, by placing terminals on
opposite sides of the connector, the inserted jack connector will
tend to become more centered and thereby may make a more reliable
contact to the detection terminals.
[0082] Turning now to FIG. 8, illustrated therein is a schematic
diagram of the accessory 14 of FIG. 1, including the control
interface 20 with the switch 22 for shorting the microphone 30
line. Also shown is the configuration of the audio plug 50
according to one possible embodiment, although in some cases other
configurations for the pin connections may be possible. For
example, the audio plug 50 shown here has a TRRS arrangement, and a
different configuration would be provided in a TRS accessory. In
some embodiments, the signals to the microphone 30 may be filtered
in order to provide better immunity towards external interference
(e.g., by using beads coupled in series with the signal lines or
capacitors in parallel with the microphone). In other embodiments,
the microphone 30 may include ESD protection, for example using a
varistor or similar protection component.
[0083] Turning now to FIG. 9, illustrated therein is a schematic
diagram of a detection circuit 90 for use with detection terminals
as generally described herein. The detection circuit 90 is an
example of a circuit that can monitor the detection terminals.
[0084] In particular, an end terminal (e.g., end terminal 61 as
shown in FIG. 5) is normally used to carry left channel audio
information to the audio accessory (e.g., audio accessory 14) via
the tip connector 52. As such, the end terminal normally does not
have a fixed voltage, and can carry an audio signal with a voltage
that can interfere with the detection of the audio accessory via
the detection terminals. Thus, a suitably configured detection
circuit can help to avoid signaling of false insertion or removal
events that might be registered depending on the audio signal being
sent through to the tip connector.
[0085] As shown, the detection circuit 90 includes a first
detection terminal 91, which could be the end terminal 61, and a
second detection terminal 95, which could be the detection terminal
65.
[0086] In this embodiment, the detection circuit 90 is adapted to
apply a bias voltage across the detection terminals 91, 95. In
particular, a bias voltage may be applied to the first detection
terminal 91 using a voltage source 96. The voltage experienced by
the second terminal 95 can be monitored, for example using a
voltage comparator 98.
[0087] More particularly, the voltage source 96 may bias the
detection terminal 91 with a voltage that is outside of the output
voltage range of the audio amplifier 92.
[0088] In particular, if the audio amplifier 92 has a maximum
output voltage of +1.8V, the bias voltage applied by the voltage
source 96 may be set to +3V or higher. Furthermore, the voltage
comparator 98 could be coupled to a reference voltage of
approximately +2.4V. These voltages could have other values as long
as the bias voltage is outside the normal range of operation of the
audio amplifier so that threshold between these values can be
made.
[0089] Accordingly, when a detection voltage is observed at the
second detection terminal 95 that exceeds the maximum normal output
voltage of the amplifier 92, the voltage comparator 98 can indicate
that an audio accessory is present. The detection circuit 90 may
indicate the detection of the presence of an audio accessory in any
fashion, such as by generating or interrupting or varying or
otherwise sending a signal (e.g., to a processor) indicating that
the accessory has been detected. In this manner, the detection
circuit 90 should provide a relative a reliable prediction about
the status of the accessory, despite large voltage variations that
might occur over the audio channel.
[0090] In some embodiments, the detection circuit 90 can include a
switch 94 for selectively activating and deactivating the detection
circuit 90. In particular, the presence of the detection circuit 90
may in some cases interfere with the quality of the audio being
sent to the audio accessory. Accordingly, the detection circuit 90
may be operable to deactivate the bias voltage (e.g., the voltage
source 96) when an audio accessory is detected. In some such cases,
the detection circuit 90 may be periodically activated to check and
see whether the accessory has been removed (e.g., once per second,
once every ten seconds, etc.)
[0091] Turning now to FIG. 10, illustrated therein is a detection
circuit 100 according to another embodiment. In this embodiment, a
controlled current source 102 is coupled to detection terminal 95.
When the detection terminals 91, 95 are connected (e.g., when the
accessory is inserted), a current will run into the audio amplifier
92, which can be detected by a current detector 103 (e.g., which
may include a comparator 104 and resistor 93).
[0092] However, when the detection terminals 91, 95 are
disconnected (e.g., the accessory is unplugged) this current source
102 will be unable to send out the current to the amplifier, and
the output will swing to the voltage rails. This swing can be
detected by direct observation or from a control voltage of the
current source, and used to indicate that no accessory is present
in the audio jack.
[0093] Turning now to FIG. 11, illustrated therein is a detection
circuit 110 according to another embodiment. The detection circuit
110 is another example of a circuit that can monitor the detection
terminals and detect a short between the detection terminals. In
this embodiment, a tone generator 112 is coupled to one of the
detection terminals (e.g., detection terminal 91), while a tone
detector 114 is coupled to the other detection terminal (e.g., the
detection terminal 95). The tone generator 112 generates one or
more tones (e.g., particular inaudible tones, such as ultrasonic
tones with a frequency greater than 20 kHz). If the tone detector
114 detects these tones, this is an indication that the detection
terminals 91, 95 have been shorted and that an accessory is
present. The detection circuit 90, such as via the tone detector
114, may indicate (e.g., to a processor) that the audio accessory
is present when the short is detected. The detection circuit 90 may
also indicate that the audio accessory is absent when the short is
absent.
[0094] In some embodiments, the inaudible tone(s) may further be
modulated with a slower envelope signal (e.g., 100 Hz) to help
suppress audible clicks that may be otherwise observed due to the
transient conditions occurring immediately at the first contact
during insertion.
[0095] In some embodiments, to lower power consumption, the
ultrasonic signal may only be emitted once in a while (e.g., once
per second, once every ten seconds, etc.) and with a low duty
cycle. In some embodiments, the audio amplifier 92 may be used to
generate or output the ultrasonic signals.
[0096] In some embodiments, the tones may have various
configurations so as to avoid possible pops, clicks or other audio
artifacts. In particular, the tones may be ultrasonic tones with
energy levels selected so as to be generally inaudible to a human
user. In some embodiments, the tone detector 114 may include
synchronized demodulation and low pass filtering in order to
protect against noise and thereby enable low amplitude levels to be
used for the ultrasonic tone.
[0097] Turning now to FIG. 12, illustrated therein is a detection
circuit 120 according to another embodiment. In this embodiment, a
zero-crossing detector 122 is coupled to the detection terminal 95
on the opposite side of the amplifier 92.
[0098] Since most audio amplifiers are AC-coupled, they will tend
to generate a zero-crossing within a finite amount of time T. The
zero-crossing detector 122 can thus monitor the second detection
terminal 95. If no zero-crossing is observed (or no low amplitude
value below a given offset or hysteresis) within a particular
amount of time (e.g., 10 milliseconds, 100 milliseconds, etc.),
this indicates that the detection terminals 91, 95 are not shorted
and no audio accessory is inserted.
[0099] In some embodiments, the detection terminal 95 may be
connected to a voltage or current source to ensure sufficient
margin against noise (similar to the configurations shown in FIG. 9
and FIG. 10).
[0100] In some embodiments, the zero-crossing detector 122 could be
a slow threshold detector with a time constant slower than the
input filter and with a detection threshold close to either the
higher or lowest supply voltage of the audio amplifier 92.
[0101] In general, the teachings herein may provide for an improved
approach to detecting whether an audio accessory is coupled to an
electronic device. More particularly, the teachings herein may be
useful to detect when an audio accessory is inserted into an
electronic device, or removed from an electronic device, or
both.
[0102] In general, concerns about lint, dust and other particles or
contaminants can be at least partially addressed by spacing apart
two or more detection terminals, making it difficult for them to be
affected by contaminants. When an audio plug is received in the
audio jack, the plug will short these terminals and indicate that
the audio accessory is coupled to the electronic device.
[0103] Even with this terminal arrangement, however, it may be
difficult to detect an audio accessory, especially when an audio
signal is active (e.g., music is being played). Accordingly, one or
more detection circuits may be used to ensure that the detected
signals at the detection terminals are indicative of the presence
of an audio accessory.
[0104] When an audio accessory is detected, and in particular when
an insertion event or removal event is detected, this information
can be used to determine whether the electronic device should make
an operational change (e.g., generating an alert, activating or
deactivating a speaker, power up an electronic device or a
component thereof, etc.)
[0105] The teachings herein may provide one or more potential
advantages as compared to prior approaches to accessory detection,
some of which have been mentioned or suggested already.
[0106] For instance, in some cases, the teachings herein may
provide for a robust and economical system that may be adaptable to
wide number of accessory configurations.
[0107] Moreover, the detection terminals and detection circuitry
may not take up significant amounts of space within a portable
electronic device (where space is often at a premium) or consume
much power on a portable electronic device (where battery life may
be a significant concern).
[0108] Furthermore, at least some embodiments may allow for the
detection of an audio accessory regardless of whether an audio
signal is present (e.g., music is playing) or not. Such a
capability may represent a notable user convenience.
[0109] The foregoing aspects of the systems, methods and electronic
devices are provided for exemplary purposes only. Those skilled in
the art will recognize that various changes may be made thereto
without departing from the scope of the method and the electronic
device as defined by the appended claims.
* * * * *